Electric current interrupting means



Sept. 13, 1932. E. KERN 1,877,753

ELECTRIC CURRENT INTERRUPTING MEANS Filed July 21, 1930 Patented Sept. 13, 1932 EBWIN KERN, OI WETTINGEN, SWITZERLAND PATENT OFFICE ELECTRIC CURRENT INTEBRUI TING MEANS Application filed July 21, 1930, Serial No. 469,417, and in Germany July 11, 1929.

This invention relates to improvements in electric circuit interrupting means and particularly to means for extinguishing a direct current are in an electric current rectifier of B the metallic vapour type.

When it is desired to quench the electric arc flowing from an anode to the cathode of an electric current rectifier, it is neces sary merely to reduce the current in the 19 cathode to such extent that the hot or cathode spot to which the arc was previously attached disappears. It has been proposed to connect condensers in parallel with the arc to accomplish the desired arc quenching which con- 15 densers act as a short circuit between the anode and cathode at the moment the con densers are connected. The current flowing into the condenser is then so great that the arc current drops to zero and the cathode 20 spot is quenched.

Research has shown that the metallic intcrior surfaces of a metallic tank enclosed rectifier in contact with the metallic vapour or which receive radiation from the cathode spot 96 which is formed, act generally like an excited cathode, i. e. a positive current may be taken from such portions. Such portions may then be used as auxiliary electrodes and may be connected, over a condenser, with the minus I 30 pole of the direct current system of the rectifier. Upon connection of the condenser, the current rushes through the condenser, instead of to the cathode spot and the cathode current must flow through the load resistance '35 which reduces the cathode current to such extent that the cathode spot is quenched.

It is, therefore, among the objects of the present invention to provide means for quenching the are flowing through an elec- 41) tric current rectifier by "the use of condensers.

Another object of the invention is to provide condensers arranged to be connected in parallel with the are for the purpose of quenching the arc flowing through an electric current rectifier.

1 Another object of the invention is to provide condensers arranged between a point of the direct current system and an auxiliary electrode or an electrode forming a portion of the rectifier.

Objects and advantages, other than those above set forth, will be apparent from the following description when read in connection with the accompanying drawing in which Figure 1 is an embodiment of the invention showing a condenser, to be connected, in the uncharged condition,

Fig. 2 is an embodiment of the invention showing a condenser so connected as to be capable of receiving a charge before being connected to the auxiliary electrode,

Fig. 3 is an embodiment of the invention showing a system in which the excitation anodes of the rectifier are cut off before the condenser is connected'to the rectifier.

Referring more particularly to the drawing by characters of reference, the reference numeral 6 designates the metallic tank forming the enclosure for anodes -7 and a, cathode 8, supported within and insulated from the tank by any of the desirable well known means, such, for example, as the ring 5 of porcelain or other suitable insulating material. All of the above forming an electric current rectifier structure. The cathode 8 is preferably of some vaporizable material having a valve action with respect to an electric current as is the case with mercury. The anodes 7 are connected and are supplied with current from the secondary winding of a transformer 9 which winding has a common neutral point.

A direct current supply system is formed by a line 11 connected with the cathode 8 and a line 12 connected with the neutral secondary point of the transformer 9, both of the lines 11 and 12 being connected with a direct current consuming device 13 completing the circuit.

The are quenching means comprises an n and 17 limit the short circuit current flowing through the condenser 18 upon closing the switch 19.

Assuming that an arc is flowing between one of the anodes 7 and the cathode 8, when the switch 19 is closed the condenser 18 is connected from the line 12 to the housing 6, the cathode 8 loses its current momentarily, and the cathode spot to which the arc was attached, disappears due to the momentary short circuit formed by the condenser.

If the switch 19 is made as adouble throw switch as shown at 19 in Fig. 2 and the condenser 18 is arranged to be connectable with both the minus and the plus sides of the direct current circuit, the condenser may be negatively charged whereupon reversal of the switch 19 to connect the condenser 18 with the housing 6 will cause the condenser to act not only as a short circuit but also as a parallel source of energy thereby further insuring the momentary absorption of all the current in the system. The condenser may be connected with any point of the system at which the potential is intermediate that of the cathode and that of the transformer secondary neutral point.

It is necessary, or at least desirable, that some means be provided whereby the current may be out off from the ignition or excitation anodes of the rectifier before or simultaneously with connection of the condenser 18 thereto. Such a means is shown in Fig. 3 in which the excitation anodes 21 are shown as being supplied from the secondary winding of a transformer 22. The mid-point of the transformer secondary winding is connected through either an ohmic or inductive resistance 23 and 24 respectively, or both, the

. coil of a relay 26 and the switch 19 with the cathode 8. The relay 26 controls a pair of contacts 27 in the circuit of the condenser 18.

When the switch 19 is opened, the no-current relay 26 drops to bridge the contacts 27 thereby closing the circuit of the condenser which then acts as above described with respect to Fig. 1. The excitation circuit is therefore opened before the condenser circuit is closed.

Among the special advantages resulting from the use of the present system are the fact that a single quenching system is sufficient to secure the desired results independently of the number of anodes present in the rectifier and also that any portion of the rectifier structure may be used as the auxiliary electrode as well as permitting the use of special structures for that purpose.

Although but a few embodiments of the present invention have been illustrated and described, it will be apparent to those skilled in the art that various changes and modifications may be made therein without departing from the spirit of the invention or from the scope of the appended claims.

The invention claimed is:

1. In a system for quenching an electric arc, a rectifier of the metallic vapor type including a metallic tank, a plurality of anodes, and a cathode insulated electrically from the tank, the anodes and the cathode forming the points of attachment for an electric are, a transformer having a neutral point and supplying current to the anodes, a condenser connectable with a conductive portion of said rectifier not normally carrying current and with a portion of said transformer at a potential lower than the cathode potential, and a. switch for connecting said condenser to quench the arc in the rectifier.

2. In a system for quenching an electric arc, a rectifier of the metallic vapor type including a metallic tank, a plurality of anodes, and a cathode insulated electrically from the tank, the anodes and the cathode forming the points of attachment for an electric arc, a transformer having a neutral point and supplying current to the anodes, a condenser connectablc with the tank of said rectifier and with the neutral point of said transformer, and a switch for connecting said condenser to quench the arc in the rectitier.

3. In a system for quenching an electric are, a rectifier of the metallic vapor type including a metallic tank, aplurality of main anodes, excitation anodes, and a cathode insulated electrically from the tank, a transformer having a neutral point and supplying current to the main anodes, a transformer supplying current to the excitation anodes and having the neutral point thereof connected with the cathode, a relay connected for energization thereof upon energization of the excitation anodes, and a condenser connectable with the tank of said rectifier and with the neutral point of the first said transformer, said relay connecting said condenser upon de-energizati0n of the excitation anodes.

1. In a control system, an electric current rectifier of the metallic vapor type compris ing a metallic container, a cathode insulated electrically from the tank, main anodes, and excitation anodes, a direct current output circuit connected with said cathode, a source of alternating current connected with said main anodes operative to establish arcs for the flow of current between said main anodes and said cathode to thereby convert said alternating current into direct current and the supply thereof to said output circuit by way of said cathode. a source of current operatively connected with said excitation anodes and said cathode to establish and maintain a path for the said flow of current by way of said main anodes and said cathode, a condenser, means operative upon actuation thereof to interrupt the operative connection a U of the said source of current with the said excitation anodes and to thereupon efi'ect the operative connection of said condenser with said container and said output circuit to establish circuit for the momentary flow of 13 current from the said main anodes to saidv container to thereby interrupt the supply of current to said output circuit by way of said cathode.

In testimony whereof I have hereunto sub- 15 scribed my name this 5th day of July, A. D.

ERWIN KERN. 

